Synthetics #22- Making Soap from Nutmeg
Preetam Ganti
Chem 213W, Fall 2018
Purpose
The purpose of this experiment was to use recrystallization to isolate trimyristin followed by a saponification reaction and in order to synthesize sodium myristate (soap) and glycerol from trimyristin (an ingredient in nutmeg). Melting point data and IR analysis was done on both the reactant and the product. Qualitative tests for the reactivity of the product were performed by using iron chloride solution and olive oil.
Introduction:
Saponification is the chemical process of converting fat or oil into soap via hydrolysis 2. This is an important process in organic chemistry because soap is used to clean the body and get rid of grease after being applied and washed away using water. Natural product isolation was a key aspect of the synthetic experiment because it involved using more biodegradable, ecofriendly products as opposed to products that might be toxic for the environment and use up too much energy.
Soap has many important uses in organic chemistry that range from cleaning to washing and bathing. It helps to get rid of oil or grease that develops from the constant exposure of your body to surroundings. Many people have water softeners in their homes in order to prevent soap scum, which is difficult to wash off easily. Soap scum is the insoluble substance created after calcium and magnesium ions in the water react with soap. In order to prevent this, a water softener provides sodium ions to replace calcium and magnesium ions, thus turning the water from “hard” to “soft”. Water softeners are very beneficial because they allow people to clean and wash without having to deal with soap scum, which is a lot more difficult to wash off.
Soap is an amphipathic molecule that consists of two ends: a polar charged end as well as a nonpolar hydrocarbon tail end. The hydrocarbon tail of soap interacts with oily germs and the germs get stored in the micelle. The micelle is what is formed when all of the hydrophobic ends of the soap molecule cluster together and the polar ends are sticking out towards the water. Because likes dissolve likes, the hydrophobic ends sticking together on the inside of the micelle is what helps oily germs to be contained in the center. These germs then get washed out with the soapy water. Figure 1 below depicts a saponification reaction to turn fat into soap.
Figure 1: Synthesis of soap from a fat via saponification reaction.1,2,4
Natural product production eliminates the use of any hazardous reagents and any production of unwanted side or byproducts. Soap can be used for bathing, washing, and cleaning. More importantly, soap helps to kill germs and remove grease and dirt from the skin9.
As previously mentioned, grease and dirt gets trapped in the center of the micelle which is formed by the hydrophobic heads turning inwards, leaving the hydrophilic heads to point outwards. This creates a surface, which is able to dissolve the oily and grease molecules and easily wash them out along with soapy water.
The hydroxide ion from sodium hydroxide attacks the carbonyl carbon on all three ends of the trimyristin, forming a tetrahedral intermediate with a negatively charged oxygen. The oxygen anion then cleaves the bond with the oxygen atoms that were initially single bonded to the carbonyl carbon. After cleavage, the detached negatively charged oxygens pull hydrogen atoms off of the carboxylic acid group to form the soap compound. The reaction runs three times because the hydroxide ion needs to attack three different carbonyl carbons within the trimyristin compound. These products form via a nucleophillic attack of the hydroxide ion as well as a reformation of bonds within the trimyristin.
Results, Discussion, and Conclusion
Saponification is an important chemical process because soap is used everyday for purposes such as washing, cleaning, and bathing. People use soap everyday whether it is to wash their hands after going to the bathroom or rid their skin of any unnecessary dirt or grease.
Recrystallization is a purification process used by organic chemists in order to remove small impurities from a solid crude product1. In recrystallization, it is important to find a suitable solvent in order to dissolve the impurities but not the compound itself. Choosing a suitable solvent requires finding a solvent that is similar in polarity to the solute but not the same polarity so that the solute does not completely dissolve. This allows the crystals in the recrystallized crude product to remain pure.
The initial step of the reaction was to purify and isolate trimyristin from nutmeg via recrystallizaiton. After purification and isolation of trimyristin, it was mixed and refluxed in order to synthesize the sodium myristate product (soap) via saponification. By refluxing the reaction, it ensured that the nucleophillic hydroxide ion would attack the trimyristin three times. This allowed for the reaction to go to completion, isolating the soap product.
In order to purify the trimyristin, the technique used was recrystallization, using ethanol as the suitable solvent for the crude product. This was difficult because the melting point of trimyristin was 57˚C, however the recrystallization was successful as crude crystals were obtained after purification. Melting point data observations, yield calculations, and IR analysis were all used to help prove the identity of the purified reactant and products.
The actual melting point stated in Sigma Aldrich5 for trimyristin is 56˚C and the observed melting point was 56.2˚C. The crude weight of the isolated trimysristin after was 2.253g percent recovery for trimyristin was 17.73%. Although this is not an optimal percent recovery, it was good that after recrystallization at least some of it was recovered.
The percent yield for the sodium myristate product was 143.9%. A possible reason for the high yield of sodium myristate can be as a result of the saponification reaction producing glycerol as another product 1. The glycerol product that was produced could have been the glycerol compound being a part of the sodium myristate product. This can be seen in the IR analysis for sodium myristate where there is a low wide peak that might account for the alcohol group of the glycerol around 3400cm-1
IR analysis was done to further analyze and prove that the isolation of trymyristin was done efficiently. The peaks depicted at 2955.31cm-1 and 2914.11cm-1 represent the carbon hydrogen bonds within the compound. The peak depicted at 1732.64cm-1 accounts for the carbon oxygen double bond (carbonyl group). The peak depicted at 1173.33cm-1 represents the carbon oxygen ester bond. The peak depicted at 1469.88cm-1 represents the scissor and/or the umbrella bend1.
After saponification, IR analysis was done on the sodium myristate product to further determine the identity of the compound via peaks that correspond to various functional groups. The peak depicted at 2917.74cm-1 and 2847.85cm-1 represent the carbon hydrogen bonds within the compound. The peak depicted at 1443.49cm-1 represent the umbrella bond of the hydrocarbon. The peak depicted at 1554.60cm-1 represents the carbon oxygen carbonyl bond. This wavelength was quite unique because the carbonyl peak is not where it should usually be depicted around 1735cm-1. This abnormal peak placement could have stemmed as a result of the two electronegative oxygen atoms being so close to one another1.
The overall experiment went well as trimyristin was successfully purified and isolated after refluxing with a percent recovery of 17.73% post recrystallization. The percent recovery from the 10g of nutmeg was 22.53%. The percent yield of the sodium myristate product was 143.9%. It was most likely over hundred percent due to the second product of the saponification process, glycerol, being mixed in with the sodium myristate product. Separation of the glycerol from the sodium myristate would allow the experimenter to obtain a lower and more realistic percent yield.
In order to observe what would happen qualitatively, the sodium myristate product was dissolved in water and the solution was added to two different test tubes. One qualitative test was the addition of several drops of olive oil to the dissolved sodium myristate in water to observe what would happen after shaking vigorously. The second qualitative test was the addition of a solution of iron chloride (FeCl3) to the sodium myristate in water to observe what would happen after agile shaking.
After adding several drops of olive oil and shaking vigorously, the solution remained clear and appeared to be more viscous when compared to before. After adding the iron chloride solution to the other test tube and agile shaking, the solution appeared to be more yellow and the product seemed to remain at the bottom of the tube as opposed to dissolving more. The solution separated into two layers as well.
Overall, the saponification synthetic experiment went well. The trimyristin was not only separated and isolated from the nutmeg, but also purified via recrystallization. The percent recovery for the trimyristin from the nutmeg was 22.5% and the percent yield for the trimyristin after recrystallization was 17.7%. The percent yield of the sodium myristate product was 143.9% and it was over 100% due to glycerol being combined with it. Melting point data and IR analysis of the trimyristin and sodium myristate product helped support the characteristics of each of the compounds.
Experimental:
Trymyristin. Ground nutmeg (10g) and diethyl ether (30mL) were both mixed and refluxed for 30 minutes. The nutmeg was vacuum filtered and removed from rest of the solution. Ether (2x20mL) was used to wash out the nutmeg. Evaporation of the ether yielded a mustard yellow product (2.25g). Recrystallization of crude trimyristin product was done using ethanol (95%, 20mL). The mustard yellow crude was collected after the solution was vacuum filtered (.399g, 17.7%). MP: 56.2˚C (lit mp 56˚C); IR (ATR) Vmax (cm-1) 2955.31, 2914.11, 1732.64, 1173.33.
Sodium myristate. Ethanol (95%, 4mL), sodium hydroxide pellets (0.04g), and trimyristin (200mg) were all mixed and refluxed for 30 minutes. The solution was poured into another solution containing distilled water (5mL) and saturated sodium chloride solution (10%, 10mL) to form into soap. After 10 minutes, the solid soap was washed with cold water (30mL) and vacuum filtered. The sodium myristate product was a chalky white color (143.9%). IR (ATR) Vmax (cm-1) 2917.74, 2847.85, 1443.49, 1554.60, 1735.
References:
1Dykstra, S.A. ; Beisewenger, K.M. ; Bischof, A.M. and Rose, H.C. Lab guide for Chemistry 213W: Introductory Organic Chemistry Laboratory; Macmillan Learning Curriculum Solutions: Plymouth, MI, 2018.
2Marcio, C. S.; Nicodem, D. E. Soap from Nutmeg: An Integrated Introductory Organic Chemistry Laboratory Experiment. J. Chem. Ed., 2002, 79, 94-95.
3Frank, F.; Roberts, T.; Snell, J.; Yates, C. Trimyristin from Nutmeg. J. Chem. Ed., 1971, 48, 255.
4Reber, Keith; Making Soap from Nutmeg. J. Chem. Ed., 2002, 79, 94-95.
5 trimyristin, SDS No: 555453; Sigma Aldrich, www.sigmaaldrich.com (accessed: 11/7/18)
6 Sodium myristate, SDS No: 822128; Sigma Aldrich, www.sigmaaldrich.com (accessed: 11/7/18)
7 glycerol, SDS No: 56815; Sigma Aldrich, www.sigmaaldrich.com (accessed: 11/7/18)
8iron chloride, SDS No: 7705080; Sigma Aldrich, www.sigmaaldrich.com (accessed: 11/7/18)
9K. C. Nicolaou, E. J. Sorensen, and N. Winssinger. The Art and Science of Organic and Natural Products Synthesis. J. Chem. Ed., 1998, 75, 1225.